Indexed by:期刊论文
Journal:EXPERIMENTAL THERMAL AND FLUID SCIENCE
Included Journals:SCIE、EI
Volume:101
Page Number:241-250
ISSN No.:0894-1777
Key Words:Falling film Reynolds number; Flow mode transition; Tube spacing; Fin structure; Integral fin tube
Abstract:This study proposed a correlation of Reynolds number (Re) for falling film mode transitions on horizontal enhanced tubes with 2D integral fms on the basis of an analysis of experimental data from current and previous studies considering the effect of tube spacing and fin structures. Transitional Re for flow mode transitions are analyzed on the basis of observing water falling film flow on four types of 2D finned tubes (ranges of fin height h, fin pitch p, and fin tip t of these tubes are 0.503-1.050 mm, 1.04-2.80 mm, and 0.31-1.27 mm) and smooth tubes under various tube spacings (s, including 6, 10, and 15 mm). Results show that large tube spacing delayed the appearance of sheet mode under increasing flow rate but prolonged the sheet mode under decreasing flow rate. This hysteresis phenomenon was enhanced by the increase in h/(p - t). The proposed correlation, which linked the transitional Re with three dimensionless groups (i.e., Galileo number (Ga), s/zeta and h/(p - t)) and a constant, predicted seven groups of transitional Re for the column-sheet and sheet within +/- 14.7%. This correlation could be applicable to the 2D finned tubes with 19 <= Ga-1/4 <= 407, 2.19 <= s/zeta 5.49, and 0.33 <= h/(p - t) <= 27.67.
Date of Publication:2019-01-01